Questions tagged [star-formation]

Questions related to the physical processes involved in or to the observations of the process of forming a star.

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7
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1answer
931 views

Why can't 'dead' galaxies start forming stars again if they merge with another, 'active' galaxy?

I heard Matthew O'Dowd mention on PBS Space-Time that dead galaxies cannot start re-forming stars even if they collect gas and/or dust from elsewhere, or even merge with another galaxy.... Why? And ...
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1answer
89 views

Has Altair flung off its planets by rotation?

This might be a dumb question, but would it be possible that during the star Altair's formation, the centrifugal forces became so large that its planets were flung away into space? Or could a passing ...
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Is there a metallicity threshold past which star formation is impossible?

I've learned that metallicity is a very important factor to consider when talking about a star's formation and lifecycle. That gets me wondering whether a high enough metallicity could prevent the ...
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47 views

How to account for the effect of Star Formation History on the inferred Stellar Initial Mass Function?

I am studying a paper The effect of star formation history on the inferred stellar initial mass function and trying to reproduce the given results. According equation (1) in the paper, the inferred ...
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31 views

Why does rotation prevent the further contraction of the cloud?

In the book Horizons: Exploring the Universe (2018) by M.Seeds and D.Backman, chapter 9, page 170-171, it states that: At least four factors resist the compression of an interstellar gas cloud, and ...
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2answers
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Could our Sun be the product of an ancient stellar collision?

The canonical model for the formation of the Solar System involves the gravitational collapse of a nebula into (perhaps) several stars across several light years. Is it possible that two or more of ...
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1answer
580 views

How much matter was ejected when the Solar System formed?

Assuming the accretion disk model for the formation of the Solar System, the most important problem, according to wikipedia, is "how the material, which is accreted by the protostar, loses its ...
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0answers
200 views

What is the birth of a star like? [closed]

Here's what I'm curious about. So this hydrogen gas collects and at some point, it eventually becomes a star. What does that process look like? If you were there as a witness to the formation of a ...
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76 views

Galactic orbits and distance between stars

In the context of whether or not nearby stars were created from the same nebula, this answer states: imagine two stars with very similar orbits, one with a period of 200 million years and the other ...
3
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2answers
146 views

After a supernova, why don't new stars coalesce with higher heavier element content?

May be a beginner's question but I couldn't find the answer anywhere. Given a supernova event and the cloud left by it, why does a new star coalesce with a disproportionally higher hydrogen(and helium)...
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2answers
4k views

Are new stars less pure as generations go by?

If stars are primarily made of hydrogen, which is then burned to helium, and then on and on and on down the chain until you either reach iron, or in extreme cases much heavier metals, this then ...
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1answer
100 views

How many generations of stars can be formed in the Stelliferous Era?

As in general case, stars are formed from nebula which in some case itself is the result of a supernova. Also stars need hydrogen to become a star (to do nuclear fusion), but stars consume hydrogen in ...
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53 views

Origin as binaries and multiple system

The majority of hot stars originate as binaries or multiple systems. How is it with the cooler spectral types? Are they usually born as single stars?
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109 views

Do stars made by universe getting smaller or larger in mass? [closed]

Do stars made by universe getting smaller or larger in mass compared to stars made 180 million years after the Big Bang? If they are getting smaller, is this due to the fact that the universe is ...
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28 views

How can you tell the rough phase of star formation a star is in from the current radius and mass of the star?

This question is really bothering me since I'm getting mixed thoughts. The masses of the stars in question are 0.92 solar masses and 0.29 solar masses. The diameters are 1,400,000 km and 750,000 km ...
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1answer
246 views

Relation between absolute magnitude of UV and star formation rate

I surfed the internet and searched a lot of sites, so far I got this but unable to find the formula which relates only Muv and the Ψ as I don't know the value of parameters Auv and μ(z). If there ...
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1answer
1k views

Why do stars rotate slower than they're expected to?

Due to conservation of angular momentum, I thought most stars would be spinning extremely fast because they have a relatively small diameter. However, it turns out that this is not true and most stars ...
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1answer
362 views

Will the Sagittarius A* Black Hole eventually swallow the entire Galaxy?

In one of his interviews, Sir Roger Penrose mentioned that when the Milky Way and the Andromeda galaxies eventually "collide" and merge into one, their super-massive black holes will also ...
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2answers
3k views

How can many stars be formed from the remains of one supernova?

A supernova is the explosion of a single star; so how is it that thousands of stars can "be born of" that one explosion (presumably only using the unspent fuel / lighter elements of the ...
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0answers
31 views

Is the magnetic field strength of a star predictable from mass, composition, age and angular momentum alone?

This answer to Which stellar properties can we describe as “first principles” in which we can derive the rest? contains an intriguing bit: That states that composition and mass are the two key ...
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1answer
60 views

Galactic winds/outflows: why and how are they detected via blueshifted absorption lines in spectra?

I know that galaxies can eject gas due to supernovae, accreting black holes, etc. These galactic "winds/outflows" are often defined/detected observationally using blueshifted absorption ...
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23 views

Are metallicities of molecular clouds lower in the outskirts of the galaxy?

(this question was originally posted in an answer by user PSR-1937-21 to another post. I find it an interesting one, but since they don't seem to be active anymore, I'm posting it to see if somebody ...
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1answer
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Why does a hot cloud need more mass to collapse?

I was wondering why does a hot cloud need more mass to collapse than a cold cloud to form a protostar? Is it because there's a higher thermal pressure inside the hotter cloud than it is in a colder ...
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1answer
48 views

Is it only possible to look at solar systems with stars at least as old as ours to be able to find intelligent life?

Assuming the speed it takes to development intelligent life is the same in all solar systems, would we need to look at exoplanets with stars as old or older than ours to find intelligent life? A young ...
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Supernova impact on Protostar formation

What would be the impact on the formation of a new star (protostar) when a nearby star (within 10 LY) goes supernova? Will the force of the explosion (once it arrives in the Molecular Cloud where the ...
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2answers
356 views

Why aren't there blue elliptical galaxies or yellow spiral galaxies?

Elliptical galaxies are universally old and yellow; about three-quarters of all ellipticals have no significant star-forming gas or dust left, and even the quarter or so of ellipticals that are still ...
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2answers
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In Orion, how close in local distance are the closest of the member stars?

All the members of Orion are within the Milky way, and some of them look pretty close to a neighbor. And could the bow* be an effect similar to the Radcliffe Wave? *shield
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Why does the star formation rate correlate with the total stellar mass in star forming galaxies?

The so-called "Main Sequence" of star-forming galaxies (e.g., Brinchmann et al. 2004; Noeske et al. 2007) clearly points to a linear relation between the stellar mass of galaxies and their star ...
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1answer
93 views

What is the difference between emission line and recombination line?

When an electron jumps from higher level to lower level a photon is emitted. This is seen as an emission line. But what exactly is a recombination line? I found them similar. Can you please tell me ...
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1answer
73 views

Very Old Stars in the Universe [duplicate]

How could a Star possibly be older than the Universe ? Is this possible or are the calculations off when determining the age of such Stars ? Can a Star exist that formed on its own independent of a ...
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1answer
124 views

What exactly are infrared dark clouds and what is the significance of the orientation of their magnetic fields?

In the video Why NASA's SOFIA Telescope On A Plane is "Perfectly Balanced" after about 10:04 SOFIA associate director James Jackson says: We have a ...
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1answer
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How much of a molecular cloud can end up as "starstuff"?

Stars form within molecular clouds. These clouds can be up to 6 millions solar masses. When the cloud collapses into stars, is it possible to know a rough figure for how much of this material actually ...
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30 views

Freefall timescale for a Jeans-unstable hydrogen cloud of mass M

I'm working on a project (personal, not academic) that involves calculating the collapse timescales for protostars which will end up becoming stars of varying given masses. I'm treating the pre-main ...
5
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1answer
185 views

Will the conditions that allow life to evolve still be around in a trillion years?

Some billions of years ago, systems like the Earth couldn't emerge and therefore life couldn't arise, because not enough of the heavy elements had formed yet. Assuming there'll neither be a big ...
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1answer
480 views

Estimating a star's radius, temperature, and luminosity based on its mass

(See updated figure and description below.) I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
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2answers
577 views

Characteristics of the first planets in the Universe?

What would have the very first planets looked like, based on their most likely chemical compositions? For example: Were they mostly grey gas giants with atmospheres of hydrogen and helium, ...
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0answers
49 views

How many parent stars contributed to our solar system? [duplicate]

All of the stuff that isn't hydrogen and helium (which came from the Big Bang), that coalesced to form our solar system (the iron, the sulfur, the water, and so forth) all came from previous ...
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205 views

Formation of the First Stars

I've got a few questions about the first stars to form in the universe. First off how might metalicity have impacted the formation of the first stars and also what effect would the absence of metals ...
4
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1answer
60 views

How to model and subtract nebular emission lines from stellar spectrum

I have optical stellar spectra from a star forming region with spatially varying nebular background. I want to subtract the nebular lines from the stellar spectra (which are varying in intensity from ...
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2answers
268 views

What will future populations of stars be like?

As stars slowly using up hydrogen and ejecting heavier elements into space, the future stars will form from nebulae that are more metal and helium rich. The question is: how does the increased ratio ...
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0answers
468 views

What is the physical reason of the mirror principle in the stellar evolution?

I understand that stars transition into the red giant phase by obeying the mirror principle, as written here: Shell-burning stars obey something called the mirror principle, which is an observation ...
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0answers
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Stars readjusting themselves in the sky [duplicate]

I had a meeting in the evening and thought of grabbing a snack before that. I stepped out of the office along with a colleague. He was on his phone and I was simply staring at the sky wishing it would ...
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0answers
62 views

Do stars come on like LEDs or wick lamps? [duplicate]

Is stellar ignition an instantaneous thing - before, dark, after, shining brightly - or more of a process over time? In fusion research 'ignition' appears to be an event, but maybe in a protostar it ...
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0answers
60 views

What is the most mass that matter likely to form?

If we plot graph between accumulate of forming mass (y-axis) and mass (x-axis), where is the maximum ? There is a story how I get this question. It start when I think about question "Is our sun is ...
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1answer
362 views

What is the lyman-werner background?

I've seen several papers that discuss the Lyman-Werner Background (LWB) when modeling star and galaxy formation in the early universe. One in particular (https://arxiv.org/abs/1803.04527) even varies ...
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1answer
73 views

How could a supernova seed solar nebula?

If the heavier elements such as Uranium came from a supernova, then this supernova had to sit somewhere right in the middle of the original solar nebula, because although the ejected matter traveled ...
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2answers
218 views

Why does star formation cease?

The universe is expected to have a time when star formation slowly ceases. However, this seems bizarre as there is always an abundant amount of matter in the Universe. Massive amounts of hydrogen ...
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1answer
64 views

Stellar nurseries in the "Shedding New Light on the Whirlpool Galaxy" video

Captions in the Hubble Space Telescope YouTube channel video Shedding New Light on the Whirlpool Galaxy say: (visible) Along the dark dust lanes, bright pink nebulae are the birthplace of new stars. (...
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2answers
4k views

Could stars form outside of galaxies?

Is it possible for there to be a dense enough nebula to form stars outside of any galaxy? Does a galaxy have a minimum size to produce stars? Or could you have a few dozen stars clustered together by ...
6
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1answer
89 views

Activity of M dwarf stars

Why are M dwarf stars the most active (in terms of starspots and faculae) of all stars?